A. Field of the Invention
The present invention relates to a sonde or detecting apparatus for a blast furnace, and more particularly, to a train of devices for inserting and withdrawing a lance into and from a blast furnace and other ancillary means for detecting the conditions in the blast furnace. The term "sonde apparatus" as used in connection with the invention refers to an apparatus for inserting and withdrawing a lance into and from a blast furnace for detecting the conditions in the furnace.
B. Description of the Prior Art
As is well known, a blast furnace is an independent metallurgical reactor. It is, however, difficult to clearly determine the phenomena occurring in the furnace. It has been considered to be very significant for the stable operation of the blast furnace to grasp and understand the charging of materials by the known bell and cup system of the prior art and the situation how the charge materials and hot blast blown from the tuyere are distributed. In this connection, it has recently become increasingly important to know the gas constituents in the furnace, the temperature of the gas, and the tendencies in the cohesive zone (softening and melting zone) of the furnace. The horizontal sonde apparatus has been developed to obtain this information.
For instance, in Japanese Laid-Open Patent Application No.99006 (1978), it is proposed that a horizontal sonde apparatus comprising a successive arrangement of a gas seal means and a curved distortion straightening means be provided on the steel shell of the blast furnace.
The horizontal sonde apparatus disclosed in this laid-open patent application has a defect in that it is susceptible to leakage of blast furnace gas. This is because the sonde apparatus makes no allowance for the bending of the lance inserted into the blast furnace. The apparatus which guides the bent lance when it is withdrawn also serves as the gas seal means and is therefore not able to absorb the bend in the lance. As a result, the seal which should properly be tightly engaged with the periphery of the lance is easily damaged, giving rise to leakage of the blast furnace gas.
Moreover, after having served its purpose in the blast furnace, the lance is withdrawn in the high temperature condition and passed through the bend straightening means where it is subjected to hot straightening. However, a fresh bend occurs in the once-straightened lance in the radiating-and-cooling step. As a result, the reuse of the lance is impossible or very difficult. That is to say, though it may be possible to insert the lance into the furnace again, insertion as far as the specified position is very difficult. Furthermore, the seal packing of the gas seal disposed at the forward end will be damaged by burning due to the heat of the lance withdrawn at the high temperature.
Furthermore, the lance is generally of an extended length and it is very difficult to insert and withdraw a long lance into and from the furnace using the arrangement described above. The lance of the prior art has other disadvantages as well. For example, it is apt to buckle when it is inserted into the furnace.